Some high-tech industries have started incorporating shape-memory alloys into various products. Today, many complex structures, such as aircraft, spacecraft, automobiles, and the like, are made from shape-memory alloys. Shape-memory alloys are special metallic materials that are capable of returning to a previously defined shape (e.g., original shape) after being heated to deformation (e.g., a deformed state).
Generally, a shape-memory alloy is in a martensite low temperature phase with a cubic crystal structure, which begins to transform into an austenite high temperature phase with a monoclinic crystal upon reaching a first austenite threshold temperature. The transformation from the martensite low temperature phase to the austenite high temperature phase is completed upon reaching a second austenite threshold temperature higher than the first austenite threshold temperature. From the austenite high temperature phase, the transformation to the martensite low temperature phase is initiated and completed after the temperature of the shape-memory alloy is cooled below first and second martensite threshold temperatures, respectively. As the shape-memory alloy transforms between the austenite high temperature phase and martensite low temperature phase, the alloy physically deforms between an original shape and a deformed shape.
Motors are used in a variety of applications, particularly those associated with aircraft control and operation. However, many conventional motors are heavy, complex, and unreliable.
The unique characteristics (e.g., pseudoelasticity and shape memory effect) of shape-memory alloys promote their use in different applications. However, the use of shape-memory alloys in motors is limited.